Doctoral Dissertation Improvement: Primate Social Behavior from an Evolutionary Neuroanatomical Perspective: A Comparative Analysis of the Amygdaloid Complex

有人认为，灵长类社会环境中固有的压力推动了人类和非人类灵长类新皮质的形成。然而，对人类和非人类灵长类动物行为的功能研究表明，为社会行为服务的神经系统既包括关键的皮质下结构，也包括特定的新皮质区域。不幸的是，这个功能系统的组成部分缺乏信息，这使得我们很难解决这些结构的进化发展问题，这些结构对人类行为如此重要。拟议的分析特别试图通过提供关于重要的皮质下结构-杏仁复合体的信息来解决这个问题。灵长类动物的杏仁核复合体在调节社会评价和相互作用中起着关键作用，并与参与社会信息处理的皮质区域高度整合。因此，这项研究的目的也反映了神经科学的范式转变，强调了皮质下边缘结构和新皮质之间的功能联系，强调了情绪和高级认知的相互依赖。拟议的形态计量分析将获得所有六个类人猿物种和三个东半球猴子物种的杏仁复合体及其五个组成核的无偏体积和神经元计数。由于这五个杏仁核与脑干、嗅觉和新皮质区域有不同的联系，它们可能会表现出不同的扩张，导致杏仁复合体的进化重组。这个项目的智力价值在于它的预定目标是增加对人类和类人猿大脑进化的理解，特别是对可能具有适应意义的区域的理解。虽然大脑是人类适应的重要场所，但我们现存的近亲--其他五种类人猿(矮黑猩猩、黑猩猩、大猩猩、猩猩和长臂猿)--的比较神经解剖学信息很少。例如，以前对杏仁复合体的分析只得出了四个单独的类人猿的体积测量。这种信息的匮乏限制了大脑进化理论的可验证性，包括那些关注社会压力和认知进化之间相互作用的理论。鉴于包括35个类人猿标本的样本是迄今为止最大的，拟议的分析非常适合于解决这些问题。此外，这个项目将广泛影响科学界，提供新的数据、学生的专业知识、组织学系列和实验室设施。它将有助于加州大学圣地亚哥分校人类学系新的湿实验室设施的开发，这将使生产其他宝贵的组织学系列的猿脑成为可能。来自加州大学圣迭戈分校和索尔克研究所的专家将向学生研究人员传授多种染色技术，以处理动物园和研究机构捐赠的稀有灵长类物种的大脑。形态计量学分析的结果将以出版的形式提供给其他研究人员，分析产生的系列也将用于其他解剖分析。总体而言，这项研究的结果预计将对生物人类学和神经科学以及更广泛的科学界产生明显的积极影响。

It has been suggested that pressures inherent in the primate social environment have driven the elaboration of the human and nonhuman primate neocortex. Yet, functional studies of human and nonhuman primate behavior indicate that the neural systems subserving social behavior include both critical subcortical structures and specific neocortical areas. Unfortunately, a dearth of information exists for components of this functional system, making it difficult to address the evolutionary development of these structures which are so essential to human behavior. The proposed analysis specifically attempts to address this problem by providing information about an important subcortical structure, the amygdaloid complex. The amygdaloid complex in primates plays a key role in mediating social appraisal and interaction and is highly incorporated with cortical areas involved in social information processing. As such, the aims of this research also reflect a paradigm shift in the neurosciences which have come to stress the functional links between subcortical limbic structures and neocortex, underscoring the interdependence of emotion and higher order cognition. The proposed morphometric analysis will procure unbiased volumes and neuron counts for the amygdaloid complex and five of its constituent nuclei in all six hominoid species and three Old World monkey species. Because these five amygdaloid nuclei are differentially connected to brainstem, olfactory, and neocortical areas, they are expected to show differential expansion resulting in evolutionary reorganization of the amygdaloid complex. The intellectual merit of this project lay in its intended goal to increase understanding of the evolution of the human and ape brain, specifically for regions that may have adaptive significance. While the brain is an important locus for human adaptation, scant comparative neuroanatomical information is available for our closest living relatives, the five other species of hominoids (bonobos, chimpanzees, gorillas, orangutans, and gibbons). For example, previous analyses of the amygdaloid complex have only produced volumetric measures for only four individual apes. This dearth of information limits the testability of theories of brain evolution, including those focused on the interplay between social pressures and the evolution of cognition. The proposed analysis is well suited to address these problems given that the sample, which includes thirty-five hominoid specimens, is the largest to date. Furthermore, this project will broadly impact the scientific community, providing new data, student expertise, histological series, and laboratory facilities. It will contribute to the development of new wet lab facilities in the UCSD Anthropology Department, which will allow for the production of other invaluable histological series of ape brains. Experts from UCSD and the Salk Institute will teach the student researcher multiple staining techniques to process the brains of rare primate species donated by zoos and research institutes. Results of the morphometric analyses will be available in published form to other researchers, and the series produced from the analysis will also be available for use in other anatomical analyses. Overall, the results of this research are expected to have a clear, positive impact on biological anthropology and the neurosciences, as well as the greater scientific community.